Determinedstretching vibrational frequencies of a triatomic molecule, i.e..Dichlorine Monoxide (Cl2O) upto third overtone by Lie algebraic method.Fundamental wavenumbers calculated model are compared with available experimental values.

Theoretical studies of the potential energy surface and bound states were performed for the N(2)O dimer. A four-dimensional intermolecular potential energy surface (PES) was constructed at the CCSD(T) level with aug-cc-pVTZ basis set supplemented with bond functions. Three co-planar local minima were found on this surface. They correspond to a nonpolar isomer with slipped-antiparallel planar st...

Raman and FTIR spectra of 6-fluoronicotinc acid (6FNA) have been analyzed using ab-initio and Density Functional Theory (DFT) calculations. Four stable structures of 6fluoronicotinc acid have been found, the structures differ in orientation of COOH with respect to the nitrogen atom. The optimized geometries, structural parameters, harmonic vibrational wave number and intensity of the vibrationa...

In order to estimate the influence of both surface and interface effects on phonon frequencies and superconducting transition temperatures in layered structures, we have calculated the vibrational modes of structures composed of alternating films of heavy and light particles. An interface effectively lowers the vibrational frequencies of the heavy particles and raises those of the light particl...

Thermodynamic properties of selected small and medium size molecules were calculated using harmonic and anharmonic vibrational frequencies. Harmonic vibrational frequencies were obtained by normal mode analysis, whereas anharmonic ones were calculated using the vibrational self-consistent field (VSCF) method. The calculated and available experimental thermodynamic data for zero point energy, en...

Vibrational studies of amino acids experimentally and theoretically have been performed. The Semi-empirical methods optimization by PM6 and RM1 on the land d-amino acids (alanine, phenylalanine, aspartic and glutamic acid), showed no difference in energy between l-and d-isomers. The vibrational frequencies were calculated by semi-emprical methods (PM6 and RM1) and ab initio methods (B3LYP/6-31+...

We present a theoretical framework for the computation of anharmonic vibrational frequencies for large systems, with a particular focus on determining adsorbate frequencies from first principles. We give a detailed account of our local implementation of the vibrational self-consistent field approach and its correlation corrections. We show that our approach is both robust, accurate and can be e...

Only one fundamental vibrational frequency of protonated carbon dioxide (HOCO(+)) has been experimentally observed in the gas phase: the ν(1) O-H stretch. Utilizing quartic force fields defined from CCSD(T)/aug-cc-pVXZ (X = T,Q,5) complete basis set limit extrapolated energies modified to include corrections for core correlation and scalar relativistic effects coupled to vibrational perturbatio...